Preparation of platinum-on-alumina catalyst composite



Jan. 1, 1957 J. A. DINWIDDIE ET AL PREPARATION OF PLATINUM-ON-ALUMINACATALYST COMPOSITE Filed March 6, 1953 FEED II CATALYST I2 I8 s 20HYDROGEN j 19 I I I HY-J o o -.o

HEATER 22 24\ nsarsn 46 DISTILLATION M:

49 33 I I .2 H!

50 CATALYST 1i CATALYST 37 36 3' n w ---m- 3 o o 0 i 3 40 COOLER \HEATERINVENTORS. James A. Dinwiddie, BY Max A Mosesman,

ATTORNEY- United States Patent PREPARATION OF PLATINUlVl-ON-ALUMINA(IATALYST CGMPOSITE Application March 6, 1953, Serial No. 340,892

4 Claims. (Cl. 252-466) The present invention is directed to a method ofpreparing an improved catalyst and a method of using same.

More particularly the invention is directed to .a method for preparing aplatinum on alumina catalyst and the use thereof in convertinghydrocarbons.

This .application is a continuation-in-part of Serial No. 318,213, iiledNovember 1, 1952, for James A. Dinwiddie and Max A, Mosesman andentitled Preparation of Im proved Alumina.

The present invention may he described briefly as involving thepreparation of aplat-inum on alumina catalyst by admixing a platinumcontaining compound with gamma alumina derived from boehmite and thenheating the admixture to a sufiicient temperature to remove any Waterassociated with the platinumacontaining compound or :gamma alumina toform a platinum on gamma alumina catalyst. The heating operation mayalso serve to decompose the platinum compound when it is susceptible tothermal decomposition.

The invention includes the method of employing the catalyst to converthydrocarbons in which a hydrocarbon boiling in the range from about 100to about 500 F. is contacted with the catalyst at a temperature in therange from about 850 F. to about 1000 F. in the presence of hydrogen ata pressure in the range from about 200 to about 750 p. s. i. g. The feedis contacted with the catalyst at a space velocity in the range fromabout 1 to about volumes of feed per volume of catalyst per hour,preferably 2 to 3 volumes of teed per volume of catalyst per hour.

The catalyst prepared in accordance with the present invention isprepared on a gamma alumina which is derived from alumina alphamonohydrate which has been given the name of boehmite. The boehmit-eused in pre paring the gamma alumina is formed from an aluminumalc-oholate by contacting the aluminum alcoholate with controlledamounts of moisture. Thus in accordance with the present invention,aluminum alcoholate may he termed by reacting aluminum metal such asaluminum turnings with an aliphatic alcohol such as one having from 1 tocarbon atoms in a molecule. The aluminum metal reacts with the alcohol,for example, methyl, ethyl,

propyl, hutyl, amyl, hexyl, heptyl and octyl alcohols and a the like ata temperature in the range from about 75 to about 300 F. Thereafter thealuminum alcoholate may be. contacted with atmospheric moisture atatmospheric temperatures or it may be contacted with steam at theboiling point of water or at a temperature above the boiling point ofwater, or it may be contacted with water at a'temperature no less thanthe temperature at which water Iboils. Thus the boiling point of watermay be less above sea level than it is at sea level or the operation maybe conducted under a reduced pressure such as with water boiling below212 -F.. It is contemplated that the present invention will includesuchoperations in which the aluminum alcoholate is hydrolyzed by contactingwith water vapor such that the aluminum alcoholate is hydrolyzed to theIboehmit-e rather-than the bayerite. The

ice

2 latter hydrate is unsuitable in the practice of the present invention.

It is contemplated in the practice of the present invention that acatalytic material such as platinum, palladium, rhodium, ruthenium,iridium and osmium, may be incorporated with the gamma alumina derivedfrom the hoehmite hydrate. The catalytic material of the typeillustrated, which is preferably platinum, may he incorporated witheither the gamma alumina or the boehmite. It the catalytic material isincorporated with the gamma alumina, it is intimately admixed therewith,and if water is present, the admixture is subjected to a heatingoperation in the range from 600 to 1600 F. to drive off water and toform a platinum on gamma alumina catalyst. If the catalytic material isadded to the hydrate, boehmite, the catalytic material such as platinumis intimately admixed therewith, the admixture is dried to remove a-nymoisture and alcohol and the admixture then subjected to a hightemperature in the range of 600 to 1600 F. to convert the boehmite togamma alumina and to form a platinum on gamma alumina catalyst.

In the process of the present invention in which the catalyst is used toconvert hydrocarbons, temperatures for the conversion operation maysuitably range from about 850 to 1000 F. while pressures will range fromabout 200 to about 750 p. s. i. g. Hydrogen or a hydrogen rich recyclegas may be used in the practice of the present invention and suitablymay he used in an amount in the range from about 2000 to about 10,000standard cubic feet per barrel of feed. The hydrocarbon may contact thecatalyst at a space velocity trom about 1 to 5 volumes of feed pervolume of catalyst per hour.

The hydrocarbon employed as a feed stock in the process of the presentinvention may be a hydrocarbon boiling from about to about 500 F. andsuitably may be a paraifinic hydrocarbon, a naphthenic hydrocarbon or an'olefinic hydrocarbon. It is preferred to use naphthenic hydrocarbons asa feed stock since the catalyst of the present invention converts thenaphthenic hydrocarbons readily to aromatic hydrocarbons. Actually thefeed stock may suitably be a mixture of paraflinic and naphthenichydrocarbons which may be converted to the more desirable aromatic andolefinic hydrocarbons. Actually the parafiinic hydrocarbons may also beconverted to desirable isohydrocarbons.

In practicing the present invention, the boehmite or gamma aluminaformed by controlled hydrolysis of an aluminum alcoholate as describedbefore may have added to it a compound or a solution of a compound ofthe various metals mentioned before. For example, when it is desired toproduce a platinum on gamma alumina catalyst, a chlorop-latinic acidsolution such as an aqueous solution of the chloroplatinic acid may beintimately admixed with the gamma alumina and the admixture thensubjected to a heating process such as to a temperature of 230 F. toremove the water and to form a platinum or platinum compound on gammaalumina catalyst. The so formed catalyst may then be pilled in asuitable pilling device to yield a composition which may be activated ata temperature of 600 to 1600 F. prior to use in fixed bed operations;this activation may be carried out either prior or subsequent tocharging the composition to a unit.

If it is desired to use the catalyst in the fluidized powder typeoperation in which the catalyst is suspended in the vaporizedhydrocarbon, it may be desirable to incorporate the platinum on thegamma alumina in a finely divided form so that the platinum on gammaalumina catalyst may be freely suspended in the vaporized hydrocarbon toallow intimate contact of the hydrocarbon with the catalyst. When afluidized powder type operation is employed, the catalyst will haveparticle sizes in the range from about 0 microns to about 100 micronswith the larger amount of the catalyst particles having diameters in therangefrom about 20to about 30 microns.

The present invention will be further illustrated by reference to .thedrawing in which. the singlefigure is a flow diagram of onemode of usingthe catalyst.

Referring now to the drawing, numeral 11 designates a charge tank inwhich a naphthenic hydrocarbon feed such as a naphtha from va Coastalcrude oil boiling in the range from about 200 to 400 F. is obtained froma source not shown. The naphtha in said tank 11 is withdrawn therefromby *line 12 containing pump 13 and is discharged into a heater orfurnace 14 and is passed through a coil15 wherein the temperature of thenaphtha is-raisedto a temperature of about 975 F. and discharged by line16 into a reactionzone 17 in which a bed of catalyst 1-8 illustrated'byplatinum on gamma alumina is arranged on a grid-plate '19. The feedstock passingdownwardly through the catalyst bed '18 is converted tomore desirable hydrocarbons.

Since the conversion of hydrocarbons in the present invention is favoredby the use of hydrogen, provision is madeto introduce'hydrogen orhydrogen rich recycle gas into the feed stock flowing through line 16into reaction zone 17. Line 20 controlled by valve 21 introduceshydrogen into the system. Since this reaction is endothermic, heat isconsumed in the reaction, and the converted product issues from thereaction zone 17 through line 22 at a temperature substantially lowerthan the temperature at which the heated feed stock enters the zone 17.For example, the temperature of the converted product in line 22 may beabout 850 F. It is, therefore, necessary to provide heat to raise thetemperature of the converted product in the present operation in which aplurality of reaction zones is employed. Therefore, a heater or furnace23 is provided and the product in line 22 is passed through a coil 24 inwhich the temperature of the product is raised to about 975 F. Thereheated product is then discharged from the heater 23 by line 25 into asecond reaction zone 26 which, like reaction zone 17, is provided-with abed of catalyst 27 arranged on a grid plate 28. The partially convertedproduct from zone 17 passes downwardly through the bed 27 and is furtherconverted. The converted product issues from reaction zone 26 throughline 29-and is passed through a third heater or furnace 30 containing acoil 31. Since the reaction in zone 27 is also endothermic and heat isconsumed, the products in line 29 are at a temperature of about 900 F.Passed through coil 31 raises the temperature back up to about 975 F.,and the converted products pass by line 32 into a third reaction zone 33in which is arranged a bed of catalyst 34 on a grid plate 35. Theconverted products from reaction zones 17 and 26 pass downwardly throughreaction Zone 33 and through the bed of catalyst 34 to cause furtherconversion of the products. The converted products issue from reactionzone 33 by line 36 at a temperature of about 940 F. The temperature ofthe converted product is then reduced rapidly by passage through acooler or condenser 37 containing a coil 38. A cooling fluid such aswater and the like is circulated through cooler 37 by lines 39 and 40.The cooled and condensed products are then discharged by line 41 at atemperature sufiicient for distillation into a distillation tower 42which, like the well-known distillation tower on the market is providedwith auxiliary equipment to allow precision fractionation of theconverted products. For example, distillation zone 42 is equipped withinternal bafiling equipment such as bubble cap trays, plates or othersimilar vapor-liquid-containing means. The distillation tower 42 is alsoprovided with a heating means illustrated by steam coil 43 foradjustment of temperature and-pressure. Tower 42 is provided with a line44 for withdrawal of fixed gases and with lines 45, 46 and 47 controlledrespectively by valves 48, 49 and 50 for withdrawal of suitableside-streams and for segregation of desiredproducts. -A heavier bottomsfraction may be withdrawn from ,tower42 :byiline .51. .Zone 42 maysuitably include flash vaporization equipment as desired. Furthermore,it is contemplated that the off gases from zone '42 may be used as thesource of hydrogen as a recycle stream in lieu of fresh hydrogen. It isto be understood that in reaction zones 17, 26 and 33 the same catalystis employed.

When employing the method of the present invention, such as with aplatinum on gamma catalyst wherein the gamma alumina is derived fromboehmite, it is unnecessary to regenerate the catalyst frequently.Inshort, the catalyst of the present invention will involve regenerationonly at long intervals. After use, the regeneration time will amount tofrom about 1 to about 10% of the operating time and ordinarily willamount to about 5% of the time of reaction. When such regeneration isrequired, this maybe accomplished simply by passing an oxygen-containinggas over the catalyst to cause oxidation or burning of any carbonaceousdeposits on the catalyst. It may be desirable to follow the regenerationtreatment by a treatment with a hydrogen-containing gas to place thecatalyst back into its original condition. Regeneration treatmentordinarily will be accomplished at a temperature of about 800 to about1200 F.

The invention will be further illustrated by the preparation of a 0.5%by weight platinum on gamma alumina catalyst. A suitable quantity ofboehmite prepared from aluminum amylate, as described after drying at230 F., was convertedto gamma alumina by heating in air at .1000" F. forabout 6 hours. To about 1600 grams of this gamma alumina there was addedml. of aqueous chloroplatinic acid solution containing 21.1 grams ofIH2PtCla.6H2O and 2250 ml. of distilled water. This .mixture was thenmulled in a jar mill for 3 hours, after which 500 ml. of water wereadded and mulling continued for about 2 hours. 300 ml. .of water wasadded to the admixture and mulling continued for 1 additional hour.Thereafter 600 mls. of water were added and mulling continued for 6hours further. 300 mls. of water were added, and the mulling continuedfor a periodof 10 hours. 700 additional mls. of water were added, andmulling was then terminated after 7 hours. Water was added batchwise inorder to provide the optimum amount of water for effective mullingwithout exceeding this amount. The mulled -mixture was thendried at 230F. for 24-hours and then formed into A pills to yield a catalyst whichonly requires activation prior to use.

This ,catalyst, after appropriate hydrogen pretreatment at reactiontemperatures, was then contacted with a hydrocarbon feed and .was foundto convert the hydrocarbons .into desirable products.

While the present invention has been illustrated by the employmentchloroplatinic acid, it is Within the spiritandscope .of the inventionto employ platinum and other catalytic metals such as illustrated beforeor compounds of such metals. For example, the soluble halides and theoxides, hydroxides and sulfides which may be-prepared in afinely-divided state (perferably colloidal) prior to addition to thesupport may be suitably used as the source of the metal employed in thepresent invention.

The nature and objects of-the present, invention having been completelydescribedyand illustrated, what we .wish to claim as new and useful andto secure by Letters Patent ;is:

1. A method of preparing a catalyst suitable for .use in hydrocarbonconversion operations which comprise admixing a solutionof aplatinum-containing compound with gamma alumina derived from aluminaalpha monohydrate, said .alumina alpha monohydrate beingobtainedlbyreacting aluminum with an aliphatic alcohol to form ;an:alcoholate and contacting said alcoholate with water *vaporvunder'conditions to hydrolyze said alcoholate to alumina alphamonohydrate and heating the admixture to a temperature in the range from600 to 1600 F. sufiicient to dry same and to form a platinum on aluminacatalyst.

2. A method of preparing a catalyst suitable for use in hydrocarbonconversion operations which comprises admixing an aqueous solution ofchlo'roplatinic acid with gamma alumina derived fromalumina alphamonohydrate, said alumina alpha monohydrate being obtained by reactingaluminum with an aliphatic alcohol to form an alcoholate and contactingsaid alcoholate with water vapor under conditions to hydrolyze saidalcoholate to alumnia alpha monohydrate, heating the admixture to atemperature of approximately 230 F. to dry same, forming the driedmixture into pills, and then heating the pills to a temperature in therange from 600 to 1600 F.

3. A method of preparing a catalyst suitable for use in hydrocarbonconversion operations which comprises admixing a solution of aplatinum-containing compound with alumina alpha monohydrate, saidalumina alpha monohydrate being obtained by reacting aluminum with analiphatic alcohol to form an alcoholate and contacting said alcoholatewith water vapor under conditions to hydrolyze said alcoholate toalumina alpha monohydrate, drying the admixture, and then heating thedried admixture to a temperature in the range from 600 to 1600 F. toobtain a platinum on alumina catalyst.

4-. A method of preparing a platinum on lumina catalyst suitable for usein hydrocarbon conversion operations which comprises mulling an aqueoussolution of chloroplatinic acid with gamma alumina derived from aluminaalpha monohydrate, said alumina alpha monohydrate being obtained byreacting aluminum with an aliphatic alcohol to form an alcoholate andcontacting said alcoholate with Water vapor under conditions tohydrolyze said alcoholate to alumina alpha monohydrate, while addingwater over a period of time sufiicient to form an intimate admixture ofsaid acid and said gamma alumina, heating the mixture to a temperatureof approximately 230 F. to dry same and to form a platinum on gammaalumina catalyst, forming said platinum on alumina catalyst into pills,and then heating said pills to a temperature in the range from 600 to1600 F.

References Cited in the file of this patent UNITED STATES PATENTS2,327,593 De Simo et al Aug. 24, 1943 2,479,110 Haensel Aug. 16, 19492,636,865 Kimberlin Apr. 28, 1953 2,636,909 Oblad et a1. Apr. 28, 19532,749,216 Dinwiddie et a1. June 5, 1956 OTHER REFERENCES ThermalTransformation of Aluminas and Aluminum Hydrates, Stumpf et al., Ind.and Eng. Chem, vol. 42 (July 1950), pages 1398-1403.

1. A METHOD OF PREPARING A CATALYST SUITABLE FOR USE IN HYDROCARBONCONVERSION OPERATIONS WHICH COMPRISE ADMIXING A SOLUTION OF APLATINUM-CONTAINING COMPOUND WITH GAMMA ALUMINA DERIVED FROM ALUMINAALPHA MONOHYDRATE, SAID ALUMINUM WITH AN ALIPHATIC ALCOHOL TAINED BYREACTING ALUMINUM WITH AN ALIPHATIC ALCOHOL TO FORM AN ALCOHOLATE ANDCONTACTING SAID ALCOHOLATE WITH WATER VAPOR UNDER CONDITIONS TOHYDROLYZE SAID ALCOHOLATE TO ALUMINA ALPHA MOIANCHYDRATE AND HEATING THEADMIXTURE TO A TEMPERATURE IN THE RANGE FROM 600*